Preparation and Electrochemical Properties of High‐Voltage Spinel LiNi 0.5 Mn 1.5 O 4 Synthesized by using Different Manganese Sources

The crystal structure and electrochemical performance of the 4.7 V cathode LiNi 0.5 Mn 1.5 O 4 (LNMO) are quite dependent on the amount of Mn 3+ and ordering of Ni/Mn in the octahedral sites. This work attempts to study LNMO synthesized by using different manganese sources, in which the valence states of manganese are +2, +2/+3, +3 and +4. A small amount of Mn 3+ existing in the spinel crystal structures of the obtained LNMO can dramatically affect the material's conductivity and electrochemical performance. Among the four studied samples, LNMO‐1 (with MnCO 3 as the manganese source) delivers the highest specific capacity of 138 mAh g −1 , higher than LNMO‐2 (Mn 3 O 4 as the manganese source), LNMO‐3 (Mn 2 O 3 as the manganese source), and LNMO‐4 (MnO 2 as the manganese source). After 100 cycles at 0.2 C, LNMO‐1 still delivers the highest discharge capacity of 129 mAh g −1 . This work provides an insight into the phenomenon of how manganese sources influence the lithium diffusion ability and crystal structure stability of LNMO as a cathode material for highly reversible lithium storage.